1. Field of the Invention
The present invention relates to surgical procedures, and, more particularly, to methods of performing surgery to alleviate the discomfort caused by temporomandibular joint syndrome.
2. Description of Related Art
Temporomandibular joint (TMJ) syndrome (or dysfunction) is a disorder of the joint between the lower jaw and the skull. The temporomandibular joint lies between the temporal bone of the skull and the mandible of the jaw, and allows the jaw to open and close. The joint is formed by a condyle, or protuberance, on the mandible, which hinges and glides in and out of the fossa, or depression, in the temporal bone (see FIG. 1).
TMJ syndrome can be caused by grinding of the teeth, malocclusion, trauma, and arthritis. There is also an indication that a posterior or backward displacement of the condyle of the jaw significantly contributes to TMJ pain [L. A. Weinberg and J. K. Chastain, J. Am. Dental Assoc. 120(3), 305 (1990)]. The effects can range from mild to severe, including pain in the joint area o that can extend to the shoulders, back, neck, and sinuses. TMJ-related headaches can also ensue, with pain sufficiently severe so as to cause nausea and blurred vision. Treatment can likewise range in extent, and may include exercise, the use of drugs or bite guards, massage, biofeedback, or electrical stimulation. Surgery is utilized in the most severe cases, which represent approximately 10% of those seeking treatment.
At present, arthroscopic techniques are prevalent in TMJ surgery. Typically, two small incisions are made in front of the ear, and a fiber-optic device is inserted into the joint. The fiber transmits an image of the joint to a screen, on which the surgeon can view the procedure indirectly without having to create the relatively large incision that would be necessary for direct visualization. Surgical implements are passed through the second incision.
Single-puncture techniques have also been taught for diagnostic arthroscopy. In these methods, a line is drawn from the mid-tragus of the ear to the lateral canthus of the eye. While the mandible is held in a protracted position, a needle is inserted into the superior joint space. The joint space is insufflated with local anesthesia with vasoconstrictors.
The maximum concavity of the glenoid fossa, which is the target for the puncture, is palpated and marked. The mandible is kept in a fully protracted position to open the posterior joint space.
A trocar is inserted into a cannula and is used to create the puncture wound, aiming at the ledge of the zygomatic arch. When the ledge is palpated by the trocar, the trocar is moved through the joint capsule with a swivelling motion. Resistance is felt until the tip of the trocar enters the joint space, at which point the trocar is removed and a blunt obturator is inserted for advancement of the cannula into the joint. The blunt obturator is used to prevent laceration of tissue, and typically advances to a depth in the range of 25 to 45 mm, after which it is removed.
The joint is then lavaged (irrigated) to remove blood, puncture debris, and synovial fluid by gradually introducing 20-25 cc of Ringer's saline solution. After flushing, an arthroscope is inserted.
Such previously used procedures require triangulation on the part of the surgeon, since the viewing means and surgical implements are inserted through nonparallel portals. In addition, the inferior joint space is normally too small for access by two rigid instruments, and thus procedures in this area must be performed "blind."